U.S. patent number 4,433,132 [Application Number 06/414,473] was granted by the patent office on 1984-02-21 for polyesters containing bis(trifluoromethyl)biphenylene radicals.
This patent grant is currently assigned to Polaroid Corporation. Invention is credited to Russell A. Gaudiana, Richard A. Minns, Howard G. Rogers.
United States Patent |
4,433,132 |
Rogers , et al. |
February 21, 1984 |
Polyesters containing bis(trifluoromethyl)biphenylene radicals
Abstract
A class of polyesters comprising recurring units having certain
bis(trifluoromethyl)biphenylene radicals is disclosed. The
polyesters exhibit favorable solubility properties in certain
organic solvents so as to facilitate the production of the
polyesters via polycondensation methods to film- and fiber-forming
molecular weights. Monomeric compounds comprising a
bis(trifluoromethyl)biphenylene radical and useful for the
production of the polyesters are also disclosed.
Inventors: |
Rogers; Howard G. (Weston,
MA), Gaudiana; Russell A. (Merrimack, NH), Minns; Richard
A. (Arlington, MA) |
Assignee: |
Polaroid Corporation
(Cambridge, MA)
|
Family
ID: |
23641603 |
Appl.
No.: |
06/414,473 |
Filed: |
September 2, 1982 |
Current U.S.
Class: |
528/191; 528/173;
528/190; 528/192; 528/206; 528/209; 528/299; 560/59; 560/83;
562/469; 562/488; 562/492; 562/853; 568/726 |
Current CPC
Class: |
C08G
63/6826 (20130101) |
Current International
Class: |
C08G
63/00 (20060101); C08G 63/682 (20060101); C08G
063/06 (); C08G 063/18 (); C08G 063/68 () |
Field of
Search: |
;528/190,191,192,206,209,173,299,306 ;260/544P ;560/59,83
;562/469,488,492 ;568/726 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lee; Lester L.
Attorney, Agent or Firm: Xiarhos; Louis G.
Claims
What is claimed is:
1. A polymer comprising recurring units of the formula ##STR33##
wherein each of A and B is a divalent organic radical and c is zero
or one; and wherein, when c is one, at least one of said A and B
divalent organic radicals is a 2,2'-bis(trifluoromethyl)
biphenylene radical having the formula ##STR34## and wherein, when
c is zero, said divalent organic radical A is a
2,2-bis(trifluoromethyl)biphenylene radical having the aforesaid
formula.
2. The polymer of claim 1 wherein said c is the integer one.
3. The polymer of claim 2 wherein one of said A and B divalent
organic radicals is a 2,2'-bis(trifluoromethyl) biphenylene radical
having the aforesaid formula and the remaining A or B radical is an
aliphatic or aromatic radical.
4. The polymer of claim 3 wherein said remaining A or B radical is
a radical having essentially coaxial chain-extending bonds.
5. The polymer of claim 2 wherein said divalent organic radical A
is a 2,2'-bis(trifluoromethyl)biphenylene radical having the
aforesaid formula.
6. The polymer of claim 2 wherein said divalent organic radical A
is a 2,2'-bis(trifluoromethyl)biphenylene radical and said divalent
organic radical B is an aliphatic or aromatic radical.
7. The polymer of claim 2 wherein said recurring units have the
formula ##STR35##
8. The polymer of claim 2 wherein said recurring units have the
formula ##STR36##
9. The polymer of claim 2 wherein said recurring units have the
formula ##STR37##
10. The polymer of claim 1 in the form of a film or fiber.
11. The polymer of claim 10 wherein the film or fiber is a
molecularly oriented stretched film or fiber.
12. The polymer of claim 2 in the form of a film or fiber.
13. The polymer of claim 11 wherein the film or fiber is a
molecularly oriented stretched film or fiber.
14. The polymer of claim 1 wherein said recurring units have the
formula ##STR38##
Description
BACKGROUND OF THE INVENTION
This invention relates to certain aromatic polyesters exhibiting
desirable solubility characteristics and useful in the production
of films and fibers. More particularly, it relates to aromatic
polyesters containing recurring
2,2'-bis(trifluoromethyl)-4,4'-biphenylene radicals and to
monomeric compounds useful in the production of such
polyesters.
The production of polyesters, including aromatic polyesters, by the
polycondensation of dicarboxylic acids (or the corresponding acyl
halides) and polyhydric alcohols has been well known. For example,
the production of such polyesters is described in U.S. Pat. Nos.
3,008,929 (issued Nov. 14, 1961 to E. A. Wielicki); in 3,786,022
(issued Jan. 15, 1974 to N. Hata et al.); in 4,066,620 (issued Jan.
3, 1978 to J. J. Kleinschuster); in 4,083,829 (issued Apr. 11, 1978
to G. W. Calundann et al.); and in U.S. Pat. No. 4,228,588 (issued
Sept. 8, 1981 to J. A. Donohue). In general, it is well recognized
that the mechanical and physical properties of polymeric films and
fibers will depend upon the chemical structure of the polymers from
which they are prepared and that such properties can be materially
influenced by such molecular factors as chain stiffness,
intermolecular forces, orientation and crystallinity. Accordingly,
there has been considerable interest in the development of
polyesters having particular structural or molecular configurations
for the realization of one or more particular properties suited to
a desired application.
In the production of polyester films and fibers, it will oftentimes
be advantageous to prepare such films and fibers from a solution of
the polyester in a common and readily available solvent material.
Frequently, and particularly in the case of wholly aromatic
polyesters, the polyester materials may be substantially insoluble.
Moreover, the insolubility of the polyester may represent a
limitation on the attainment of film- and fiber-forming molecular
weights owing to the tendency of the polyester to precipitate from
a solution polycondensation medium without attaining the requisite
molecular weight for such film or fiber formation. Accordingly, the
characteristic and advantageous properties of a polyester suited to
a particular application will be more readily realized where the
polyester material exhibits solubility in readily available organic
solvents and can be polymerized to film- and fiber-forming
molecular weights in such solvents.
SUMMARY OF THE INVENTION
The present invention provides a class of polymeric materials
exhibiting solubility in common organic solvents, such as in
dimethylacetamide or tetrahydrofuran, and is based in part upon the
discovery that the incorporation into a polyester of recurring
2,2'-bis(trifluoromethyl)-4,4'-biphenylene radicals imparts to the
polyester material certain desired solubility characteristics which
facilitate the formation of the polyester by solution
polycondensation and the production of films and fibers.
Transparent films and fibers exhibiting certain optical properties,
e.g., birefringence, can be provided. The present invention, thus,
provides a class of polymers comprising recurring units of the
formula ##STR1## wherein each of A and B is a divalent organic
radical and c is zero or one; and wherein, when c is one, at least
one of said A and B divalent radicals is a
2,2'-bis(trifluoromethyl) biphenylene radical having the formula
##STR2## and wherein, when c is zero, said divalent radical A is a
2,2'-bis(trifluoromethyl)biphenylene radical having the aforesaid
formula.
According to another composition aspect of the present invention
there is provided a novel class of monomers of the formula ##STR3##
wherein each of X.sup.1 and X.sup.2 is independently --OH; or
##STR4## where Z is halogen or --OR, and R is hydrogen or alkyl.
The novel monomers are useful in the production of the novel
polymers of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
As described hereinbefore, the polyesters of the present invention
comprise recurring units of the formula ##STR5## wherein c is zero
or one. It will be appreciated from inspection of Formula I that
the following recurring units are contemplated when c is the
integer one: ##STR6## In such recurring units, at least one of
divalent radicals A and B will comprise a
2,2'-bis(trifluoromethyl)-4,4'-biphenylene radical having the
formula ##STR7## For purposes of convenience, the
2,2'-bis(trifluoromethyl)-4,4'-biphenylene radical of Formula II,
and any such radical containing additional substituent groups, is
referred to hereinafter as a bis(trifluoromethyl) biphenylene
radical.
While applicants do not wish to be bound by precise theory or
mechanism in explanation of the solubility properties observed in
polyesters containing a bis(trifluoromethyl) biphenylene radical,
it is believed that the solubility of such polyesters is
importantly related to the presence of trifluoromethyl groups at
the ortho positions of the inter-bonded aromatic nuclei of a
bis(trifluoromethyl) biphenylene radical. The large steric effects
of the trifluoromethyl substituents are believed to confer or
promote a condition of non-coplanarity with respect to the aromatic
nuclei thereof, i.e., a molecular configuration whereby the
trifluoromethyl-substituted interbonded aromatic nuclei are in
different planes. The presence of such nuclei or rings in "twisted"
configuration relative to one another is also believed to provide a
distribution of high electron density cylindrically or
ellipsoidally about the long axis of a recurring unit containing
the bis(trifluoromethyl)biphenylene radical and a rigid rod-like
oriented polymer resulting from the end-to-end joining of such
recurring units. This distribution is believed to contribute at
least in part to optical anisotropy or birefringence in such rigid
rod-like polymers.
When only one of radicals A and B in the recurring unit ##STR8## is
a bis(trifluoromethyl) biphenylene radical, the remaining divalent
radical A or B can comprise any of a variety of divalent organic
radicals so long as the solubility-promoting influence of the
bis(trifluoromethyl) biphenylene radical is not effectively negated
in the resulting polyester. In general, where only one of the A and
B organic divalent radicals is a bis(trifluoromethyl) biphenylene
radical, the other or remaining A or B radical can be a divalent
aliphatic or aromatic moiety. For example, the aliphatic radical
can be an alkylene radical having from 2 to about 12 or more carbon
atoms in the alkylene chain and can be branched or unbranched. The
alkylene radicals derived from such polyhydric alcohols as ethylene
glycol, 1,2-propylene glycol, 1,3-propylene glycol, butylene
glycol, hexamethylene glycol or the like are exemplary of such
alkylene radicals.
Suitable aromatic divalent radicals include those having at least
one benzene ring, i.e., a six-carbon benzene ring, a fused aromatic
radical such as naphthylene, or a radical comprising interbonded
phenylene rings such as biphenylene. The aromatic divalent radicals
can also include those where the aromatic nuclei are interbonded
through a divalent moiety such as a methylene, ether, sulfide or
sulfone moiety. Examples of such radicals are the diphenylene
ether, diphenylenemethane, diphenylenesulfide and
diphenylenesulfone radicals. It will be appreciated that such
aliphatic or aromatic divalent radicals can be substituted, for
example, by alkyl, halogen or other substituent moieties. A
preferred substituted aromatic radical is the
2-chloro-1,4'-phenylene radical.
When only one of the A or B radicals in the recurring unit of
Formula IV is a bis(trifluoromethyl)biphenylene radical, the nature
of the remaining A or B radical will be determined largely by the
particular properties desired in the polyester. For example, it may
be desired to utilize the polyester as a birefringent layer in an
optical device, in which case, the remaining radical A or B will be
a radical which confers a rigid rod-like character to the polyester
resulting from a recurring unit of Formula IV. In general, the
remaining A or B radical will in this case be a divalent radical
having essentially coaxial chain-extending bonds. For example,
aromatic radicals having para-oriented chain-extending bonds will
be suited to the provision of polymers having a rigid rod-like
character. Radicals having a flexible character such as alkylene
radicals and biphenyl radicals interbonded through methylene,
ether, sulfone, sulfide or like group will not be suitable where a
rigid rod-like polymer is desired. Suitable divalent radicals
having essentially coaxial chain-extending bonds and suited as the
remaining A or B radical for the production of rigid rod-like
polymers include such radicals as 1,4-phenylene;
2-chloro-1,4-phenylene; 4,4'-biphenylene; substituted, e.g.,
halo-substituted 4,4'-biphenylene radicals; a stilbene radical such
as ##STR9## and corresponding substituted, e.g., chloro- or
bromo-substituted stilbene radicals. Also suitable are
trans-vinylene; ethynlene; and polyunsaturated divalent radicals
conforming to the formula ##STR10## where n is an integer of at
least two (e.g., two or three) and each of D and E is hydrogen or
alkyl (e.g., methyl) and inclusive of such polyunsaturated divalent
radicals as trans-trans-1,4-butadienylene, i.e., ##STR11## and
1,4-dimethyl-trans-trans-1,4-butadienylene, i.e., ##STR12## Other
suitable radicals for this purpose are disclosed in the U.S. patent
application of H. G. Rogers et al., Ser. No. 238,069, filed Mar. 2,
1981, and now U.S. Pat. No. 4,384,107; in the U.S. patent
application of H. G. Rogers et al., Ser. No. 238,054, filed Mar. 2,
1981; and in the U.S. patent application of R. A. Gaudiana et al.,
Ser. No. 239,180, filed Mar. 2, 1981, and now U.S. Pat. No.
4,393,194.
Where the optical properties of a polyester hereof are not of
paramount importance to a particular application, considerable
latitude in the nature of the remaining A or B radical will be
permitted where only one of the A or B radicals is a
bis(trifluoromethyl)biphenylene radical hereof. For example, where
the polyester is to be used as a plasticizer for other polymers, or
for the production of certain fibers or films where birefringence,
refractive or like optical properties are not required, radicals
such as 1,3-phenylene as can be derived from isophthalic acid, and
radicals such as alkylene or biphenyl radicals interbonded through
a methylene, ether, sulfone or like linkage, can be utilized.
Inclusive of polyesters of the present invention represented by the
structure of Formula IV are those containing recurring units
represented by the following structures. It will be appreciated
that one or more hydrogen atoms of each aromatic nucleus of the
2,2'-bis(trifluoromethyl)-4,4'-biphenylene radical can, if desired,
be replaced with a substituent group such as alkyl, halo (e.g.,
chloro, bromo, iodo, fluoro), nitro or the like. ##STR13##
From inspection of the general formula set forth as descriptive of
recurring units of the polyesters hereof, i.e., recurring units of
the formula ##STR14## it will be appreciated that, when c is zero,
the recurring unit will be represented by the following formula:
##STR15## wherein A is a bis(trifluoromethyl) biphenylene radical
as hereinbefore described. Accordingly, such a polyester will be a
polymer of a recurring unit as follows which contains a
bis(trifluoromethyl)biphenylene radical: ##STR16##
While the polyesters described hereinbefore can consist essentially
of recurring units represented by the structures of Formulas IV and
XVI, i.e., ##STR17## a combination of such recurring units, the
polyesters hereof can also comprise recurring units not conforming
to the described structures of Formulas IV and XVI. Examples of
recurring units which do not conform to such descriptions and which
can be present in such polyesters in proportions which do not
undesirably reduce the solubility of the polymeric material
include, for example, recurring units having the formula ##STR18##
wherein each G is a divalent radical other than a
bis(trifluoromethyl) biphenyl radical such as 1,4-phenylene;
4,4'-biphenylene; vinylene;
trans,trans-1,4-dimethyl-trans,trans-1,4-butadienylene or
2,4'-trans-vinylenephenylene.
The polyesters of the present invention can be prepared by resort
to a solution polycondensation or melt polycondensation reaction
depending upon the melting point or solubility of the particular
reactants employed. In general, the polyesters can be prepared by
reaction of a dicarboxylic acid (or corresponding acid halide or
alkyl ester) with a polyhydric alcohol according to generally known
polycondensation methods. For example, polyesters of the type
represented by the structure of Formula IV can be suitably prepared
by the reaction of a dicarboxylic acid halide of the formula
##STR19## with a polyhydric alcohol of the formula HO-B-OH, where
Hal represents halogen, such as chloro or bromo, and A and B have
the meanings set forth hereinbefore.
In the case, for example, of a solution polycondensation reaction,
the polyester can be obtained by reaction of the diacid halide with
the polyhydric alcohol in a suitable inert organic solvent and in
the presence of a catalyst (or acid acceptor) which neutralizes
hydrogen chloride formed, e.g., pyridine.
An inert organic solvent is utilized to dissolve the polyester
produced by the polycondensation reaction. Suitable solvents
include chloroform, methylene chloride, 1,2-dichloroethane,
1,1,2,2-tetrachloroethane, dimethylsulfoxide, N,N-dimethylformamide
and acetone. In general, the polyester is obtained by reaction of
one mole of the polyhydric alcohol (or a mixture of polyhydric
alcohols) with 1.0 to 1.05 moles of the diacid halide in the
organic solvent and in the presence of at least two moles of the
acid acceptor. The polycondensation can be conducted at a
temperature of about 20.degree. C. to about 150.degree. C. or
higher depending upon the boiling point of the solvent. Suitable
acid acceptors include the tertiary amines, such as the trialkyl
amines, e.g., trimethylamine; or heterocyclic amines, e.g.,
pyridine.
The polyesters hereof can also be prepared by a known melt
polycondensation technique whereby one mole of a diacetate of the
polyhydric alcohol is reacted with 1.0 to 1.1 moles of the
dicarboxylic acid in the presence of a catalyst. The reaction
mixture is heated in a stream of inert gas, e.g., nitrogen, to a
reaction temperature between the melting temperature and the
decomposition temperature of the monomers and the reaction pressure
is reduced to below about 60 mm. Hg for removal of acetic acid
produced by the reaction. Further heating above the melting
temperature of the polyester product and reduction of the reaction
pressure to below about 5 mm. Hg. results in additional removal of
acetic acid by-product. Organometallic compounds such as titanium
dioxide, antimony trioxide and butyl orthotitanate can be suitably
employed as catalysts for the melt polycondensation reaction.
Polyesters of the present invention can also be prepared by an
ester interchange according to generally known procedure. Thus, one
mole of a dialkyl ester of the dicarboxylic acid can be reacted
with from about 1.1 to about 2.5 moles of polyhydric alcohol,
generally at atmospheric pressure, although subatmospheric or
superatmospheric conditions can be employed. Suitable catalysts for
the ester interchange reaction, which is generally conducted over a
range of from about 90.degree. C. to 325.degree. C., include
calcium acetate, sodium methoxide, antimony trioxide and
tetraisopropyl titanate. During the ester interchange reaction,
methanol is removed as a by-product and heating is continued to
effect the polycondensation.
The preparation of polyesters hereof can be illustrated by the
following reaction schemes: Reaction 1(a) involving the solution
polycondensation of chlorohydroquinone and
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarbonyl chloride in
1,1,2,2-tetrachloroethane (TCE) solvent using pyridine as an acid
acceptor; and Reaction 1(b) involving the high-temperature ester
interchange melt polycondensation of ethylene glycol and dimethyl
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate using calcium
acetate and antimony trioxide as transesterification catalysts.
##STR20##
Polyesters containing recurring units having the structure
represented by Formula XVI, i.e., ##STR21## can be prepared, for
example, by the polymerization of
2,2'-bis(trifluoromethyl)-4-hydroxy-4'-biphenyl carboxylic acid
with the aid of an esterification catalyst or by employing a
carbonyl halide thereof and an acid acceptor. This polymerization
is illustrated by reference to the preparation of
poly(2,2'-bis(trifluoromethyl)-4,4'-carboxylate in accordance with
the following reaction scheme: ##STR22##
The polyesters of the present invention are conveniently prepared
from certain novel monomeric compounds of Formula III, i.e.,
compounds having the formula ##STR23## wherein each of X.sup.1 and
X.sup.2 is independently --OH; or ##STR24## where Z is halogen
(e.g., chloro, bromo) or --OR, and R is hydrogen or is alkyl (e.g.,
methyl, ethyl, octyl). It will be seen that X.sup.1 and X.sup.2 can
be the same (e.g., both --COOH) or different (e.g., X.sup.1 is
--COOH and X.sup.2 is --OH).
Preferred monomeric compounds exemplary of the compounds of Formula
III include the following: ##STR25##
The monomeric compound of Formula XVII, i.e.,
2,2'-bis(trifluoromethyl)-4,4'-dihydroxybiphenyl, can be prepared
from a known starting material, i.e.,
2,2'-bis(trifluoromethyl)-benzidine (reported by M. R. Pettit and
J. C. Tatlow, J.Chem. Soc., 1951, pp. 3459-3464; and by R. A.
Cartwright and J. C. Tatlow, J.Chem. Soc., 1953, pp. 1994-1998).
This starting material can be converted to a tetrazonium
tetrafluoroborate using sodium nitrite and tetrafluoroboric acid
which can then be decomposed in refluxing trifluoroacetic acid
containing potassium trifluoroacetate according to the procedure
reported by D. E. Horning, D. A. Ross and J. M. Muchowski, Can. J.
Chem., 51, 2347 (1973). The preparation of the compound of Formula
XVII is illustrated by the following reaction scheme: ##STR26##
The monomeric compound of Formula XVIII, i.e., dimethyl
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate, can be
prepared starting from 2,2'-bis(trifluoromethyl)-benzidine by (a)
conversion to the tetrazonium salt using sodium nitrite and acid,
e.g., sulfuric acid and conversion of the tetrazonium salt to
2,2'-bis(trifluoromethyl)-4,4'-diiodobiphenyl by reaction in a
solution of sodium iodide and iodine; and (b) carboalkoxylation of
the diiodo compound using, for example, carbon monoxide in methanol
and triethylamine with 2 mole % dichlorobis(triphenylphosphine)
palladium (II) according to the procedure of A. Schoenberg, I.
Bartoletti and R. F. Heck, J. Org. Chem., 39, 3318 (1974). The
production of the compound of Formula XVIII is illustrated by the
following reaction scheme: ##STR27##
The dicarboxylate of Formula XVIII can be utilized to prepare other
monomeric compounds of the invention. For example, saponification
of the dicarboxylate using sodium hydroxide and acidification of
the resulting salt provides the corresponding diacid of Formula XX
according to the following reaction scheme: ##STR28##
The acid dichloride corresponding to the diacid of Formula XX,
i.e., 2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarbonyl chloride
(Formula XIX) can be prepared by the known reaction of the acid
with thionyl chloride: ##STR29##
The polyesters of the present invention are especially advantageous
from the standpoint of their solubility in such common and readily
available solvents as tetrahydrofuran and dimethylacetamide. The
improved solubility of the bis(trifluoromethyl)biphenylene
polyesters of the invention, relative to wholly aromatic polyesters
in general, permits improved handling of the polymers and
facilitates the production of polymeric layers which can be coated
from a suitable solvent material and made to conform to a desired
shape or conformation suited to a particular application. Films and
coated or other shaped forms of the polyesters can be redissolved
and reshaped or refabricated if desired. Depending upon the nature
of other recurring units as may be present in the polyester
materials, and the nature of the solvent desirably employed, the
solubility characteristics of the polyesters hereof can be varied
or controlled to suit particular applications.
In general, and as reported in U.S. Pat. No. 4,083,829 (issued Apr.
1, 1978 to G. W. Calundann et al.), wholly aromatic polyesters tend
to be substantially insoluble in common polyester solvents such as
hexafluoroisopropanol and o-chlorophenol and are generally not
susceptible to solution processing. The incorporation of
trifluoromethyl substituent groups into wholly aromatic polyesters,
e.g., into polyesters comprising recurring units of Formula IV
wherein both A and B divalent radicals are aromatic radicals, thus,
permits the realization of solubility and solution processing that
otherwise may not be available.
The polyesters of the present invention can be variously formed or
shaped into films, sheets, coatings, layers, fibrils, fibers or the
like. For example, a solution of polyester as described
hereinbefore, in a solvent material such as tetrahydrofuran can be
readily cast onto a suitable support material for the formation of
a polymeric film or layer of the polyester material. The polymeric
film can be utilized for the production of a birefringent polymeric
film or sheet material which can be utilized in various optical
devices. Thus, a polymeric film or sheet material can be subjected
to stretching so as to introduce molecular orientation and provide
a film material having a birefringent character.
The polyesters of the present invention can also be formed into
fibers, fibrils or the like by extrusion or spinning methods known
in the art. Thus, for example, a solution of the polyester can be
extruded or spun into a coagulating bath for coagulation of the
polymeric material into the form of fibers which can be cut,
stretched or assembled into fiber tows or bundles as desired. The
fibers, fibrils, tows or the like can be washed for removal of
residual solubilizing agents, solvents, extruding or spinning aids
and dried to materials exhibiting birefringent and other desired
properties.
Where a molecular orientation is permanently induced in the
polyester material, as by formation of the polyester into an
oriented sheet, fiber or other form, the polyester will exhibit
optical birefringence which can be measured in accordance with a
number of known methods. Known shaping or forming methods can be
utilized for the orientation of polymeric materials of the present
invention. Preferably, this will be accomplished by unidirectional
stretching of a polymeric film, by extrusion of the polymer into a
sheet, layer or other stretched form, or by the combined effects of
extrusion and stretching. In their oriented state, the polymers of
the invention exhibit birefringence and, in general, greater
birefringence will be observed in the case of polymeric materials
exhibiting a greater degree of molecular orientation.
The polymeric materials of the present invention, in addition to
exhibiting desired solubility, are advantageous from the standpoint
of their transparency. In contrast to polymeric materials which
become decidedly opaque as a result of stretching, the polyesters
hereof in general exhibit optical transparency in unoriented and
stretched forms. For example, the polyesters hereof exhibit a high
transparency and a low order of light scattering, exhibiting a
ratio of amorphous to crystalline material of from about 10:1 to
about 20:1 by weight. These materials are, thus, suited to optical
applications where a light-transmissive material is desirably
utilized.
The polyesters of the present invention can be utilized in the
construction of a variety of optical filter or other devices. In
general, such devices are multilayer devices which include a layer
of molecularly oriented and birefringent polymeric material and, in
addition, at least one other layer of isotropic or birefringent
material. The polyesters of the invention exhibit birefringence and
can be suitably employed in the construction of such devices. The
additional layer or layers of such devices, whether isotropic or
birefringent, will generally comprise materials having an index of
refraction matching substantially one index of refraction of the
birefringent polymeric material of the invention. For example, a
layer of isotropic material having an index of refraction matching
substantially one index of refraction of the birefringent layer can
be suitably bonded to the layer of highly birefringent polymer. A
preferred device comprises a layer of the molecularly oriented and
birefringent material of the invention bonded between two layers of
isotropic material, the index of refraction of each isotropic layer
constituting substantially a match with an index of refraction of
the molecularly oriented and birefringent material. Such a
preferred device can be utilized for the polarization of light and
may be termed a "total transmission" light polarizer, i.e., one
which is particularly adapted to polarize a very large portion of
incident light. Total polarizers find application in equipment such
as may be employed for signaling, projection and display purposes,
or the like, and in antiglare systems for automotive vehicles.
According to another application of the polymeric materials of the
present invention, a plurality of alternating isotropic and
birefringent layers can be utilized for the production of a
multilayer light polarizing device, at least one of the layers of
birefringent material comprising a molecularly oriented and highly
birefringent material as defined herein. Such a device can be
utilized as a multilayer polarizer which partly transmits and
partly reflects incident light as separate linearly polarized
components vibrating in orthogonal directions.
Optical devices in which the polyesters of the invention can be
utilized, and their methods for construction and modes of operation
are described in detail in the aforementioned U.S. patent
application of H. G. Rogers et al., (U.S. Ser. No. 238,054, filed
Mar. 2, 1981). Examples of other devices which can be adapted to
include a polymeric and birefringent layer as described herein are
described, for example, in U.S. Pat. Nos. 34,506,333 (issued Apr.
14, 1970 to E. H. Land; in 3,213,753 (issued Oct. 26, 1965 to H. G.
Rogers); in 3,610,729 (issued Oct. 5, 1971 to H. G. Rogers); in
3,473,013 (issued Oct. 14, 1969 to H. G. Rogers); in 3,522,984
(issued Aug. 4, 1970 to H. G. Rogers); in 3,522,985 (issued Aug. 4,
1970 to H. G. Rogers); in 3,528,723 (issued Sept. 15, 1970 to H. G.
Rogers); and in 3,582,424 (issued June 1, 1971 to K. Norvaisa).
The following non-limiting examples are illustrative of the present
invention. All percentages are by weight except as otherwise
indicated.
EXAMPLE 1
This Example illustrates the preparation of
2,2'-bis(trifluoromethyl)-4,4'-dihydroxybiphenyl.
A 48% (by weight) aqueous solution of tetrafluoroboric acid (6.7
ml.) was added to 10 mls. of water and 3.2 grams (0.01 mole) of
2,2'-bis(trifluoromethyl)benzidine were dissolved therein. The
resulting solution was cooled to 0.degree. C. and a solution of 1.4
grams sodium nitrite (0.02 mole) in 3 mls. water was added dropwise
with stirring over a ten-minute period. The resulting paste was
stirred for ten minutes at 0.degree. C. and was filtered. The
product, white tetrazonium salt, was washed with ice-cold 10%
aqueous tetrafluoroboric acid (ten mls.), ice-cold methanol (ten
mls.) and ether and was then dried under vacuum at room temperature
to yield 4.98 grams (96%) of salt product.
The salt as prepared above was added to a solution of anhydrous
potassium carbonate (1.4 grams; 0.01 mole) in trifluoroacetic acid
(50 mls.) in a three-necked round bottom flask equipped with a
magnetic stirrer, reflux condenser and a supply of nitrogen gas.
The solution was stirred under nitrogen at reflux temperature until
it gave a negative test for tetrazonium salt (alkaline
.beta.-naphthol, two days). Excess trifluoroacetic acid was then
evaporated and the residue was dissolved in 5% aqueous sodium
hydroxide (150 mls.). Some insoluble potassium tetrafluoroborate
was removed by filtration and the filtrate was washed two times
with ether (50 mls. each time), was acidified in the cold with
concentrated hydrochloric acid and was extracted three times with
ether (3.times.50 mls.). The combined extracts were dried over
sodium sulfate and evaporated to an oil. Flash chromatography over
silica gel with 1% ether in methylene dichloride yielded a yellow
oil which slowly crystallized. The solid was triturated under
pentane, filtered and dried to yield 1.8 grams (57%) of pale yellow
solid having a melting point of 152.degree.-152.5.degree. C. Two
sublimations at 125.degree. C. (<5 microns) failed to remove all
of the yellow color or to change the melting point.
Elemental analysis for C.sub.14 H.sub.8 F.sub.6 O.sub.2 provided
the following:
______________________________________ % C % H % F
______________________________________ Calculated 52.19 2.50 35.38
Found 51.89 2.74 35.17 ______________________________________
The structure of the product, i.e.,
2,2'-bis(trifluoromethyl)-4,4'-dihydroxybiphenyl having the
structure shown in Formula XVII was confirmed by nuclear magnetic
resonance (NMR) and infrared (IR) spectrophotometric analyses.
EXAMPLE 2
This Example illustrates the preparation of dimethyl
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate.
Part A.--Preparation of
2,2'-bis(trifluoromethyl)-4,4'-diiodobiphenyl
Ten grams of 2,2'-bis(trifluoromethyl)-benzidine (0.0312 mole) were
dissolved in water (100 mls.) and concentrated sulfuric acid (60
mls.) and the solution was cooled to 0.degree. C. A solution of
sodium nitrite (4.5 grams; 0.0652 mole) in water (ten mls.) was
added dropwise with stirring. The resulting cold tetrazonium salt
solution was added slowly to a stirred solution of sodium iodide
(20 grams) and iodine (20 grams) in water (20 mls.) maintained at a
temperature of 0.degree. C. During the addition, methylene
dichloride was added to keep the product in solution. After
stirring the mixture overnight at room temperature, excess iodine
was destroyed by adding sodium bisulfite and the product was
extracted with methylene dichloride. The organic phase was washed
with aqueous sodium bisulfite, dried and evaporated to yield 13.3
grams (78%) of product, i.e.,
2,2'-bis(trifluoromethyl)-4,4'-diiodobiphenyl, having a melting
point of 119.degree.-122.degree. C. Recrystallization from methanol
yielded white prisms having a melting point of
121.degree.-123.degree. C.
Elemental analysis for C.sub.14 H.sub.6 F.sub.6 I.sub.2 provided
the following:
______________________________________ % C % H % F % I
______________________________________ Calculated 31.02 1.12 21.03
46.83 Found 31.03 0.93 20.13 47.71
______________________________________
The structure of the product was confirmed by NMR and IR
spectrophotometric analyses.
Part B.--Preparation of dimethyl
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate
Seven grams (0.0129 mole) of
2,2'-bis(trifluoromethyl)-4,4'-diiodobiphenyl, as prepared in Part
A hereinbefore, 183 mgs. (0.00026 mole) of
dichlorobis(triphenylphosphine) palladium (II), 5.5 mls. (0.039
mole) of triethylamine and 65 mls. of methanol were stirred at
55.degree. C. under one atmosphere of carbon monoxide for 18 hours.
The solvent was evaporated and the residue was dissolved in hexane,
treated with Norit (activated carbon) and filtered in a Soxhlet
extractor. Flash chromatography of the filtrate over silica gel
with methylene dichloride/hexane (1:1 by vol.) yielded an amber oil
which was crystallized from methanol at -60.degree. C. to yield 3.8
grams (73%) of white product having a melting point of
71.degree.-72.degree. C.
Elemental analysis for C.sub.18 H.sub.12 F.sub.6 O.sub.4 provided
the following:
______________________________________ % C % H % F
______________________________________ Calculated 53.21 2.98 28.06
Found 53.10 2.74 27.98 ______________________________________
The structure of the product, i.e., dimethyl
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate having the
structure shown in Formula XVIII, was confirmed by NMR and IR
analyses.
EXAMPLE 3
This Example illustrates the preparation of
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylic acid.
Two grams (0.0049 mole) of dimethyl
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate were
dissolved in 20 mls. of methanol and four mls. of 50% by wt.
aqueous sodium hydroxide. The solution was heated to boiling with
stirring and 100 mls. of water were added over a one-hour period to
maintain a clear solution as methanol was distilled off. When the
vapor temperature reached 99.degree. C., the solution was cooled
and acidified with concentrated hydrochloric acid to yield a coarse
precipitate which was filtered, washed with water and dried. The
product, obtained in an amount of 1.77 grams (95%), had a melting
point greater than 300.degree. C.
The structure of the product, i.e.,
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylic acid having
the structure shown in Formula XX, was confirmed by NMR and IR
spectrophotometric analyses.
EXAMPLE 4
This Example illustrates the preparation of
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarbonyl chloride.
A reaction mixture of 2.5 grams (0.0066 mole)
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylic acid, prepared
as described in Example 3 hereof, 30 mls. of thionyl chloride and
one drop dimethylformamide were stirred under reflux for four
hours. Excess thionyl chloride was then distilled off and the
residual oil was dissolved in pentane, filtered and blown dry with
nitrogen to effect crystallization of the product. Drying in vacuo
provided 2.6 grams (95%) of product exhibiting a melting point of
52.degree.-54.degree. C. Molecular distillation at
80.degree.-100.degree. C. (<5 microns) provided white crystals
(2.3 grams, 84%) exhibiting a melting point of
55.degree.-56.degree. C.
Elemental analysis of the product for C.sub.16 H.sub.6 Cl.sub.2
F.sub.6 O.sub.2 provided the following:
______________________________________ % C % H % Cl % F
______________________________________ Calculated 46.29 1.46 17.08
27.46 Found 46.24 1.82 17.17 27.39
______________________________________
The structure of the product, i.e.,
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarbonyl chloride having
the structure shown in Formula XIX, was confirmed by NMR and IR
spectrophotometric analyses.
EXAMPLE 5
This Example illustrates the polycondensation of chlorohydroquinone
and 2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarbonyl chloride,
i.e., the preparation of poly(chloro-1",4"-phenylene
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate).
Chlorohydroquinone (sublimed; 312 mgs.) was dissolved in 2.5 mls.
of 1,1,2,2-tetrachloroethane (TCE) and 0.6 ml. of pyridine under an
argon atomosphere. A solution of 896 mgs. of
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarbonyl chloride in 2.5
mls. of TCE was then added dropwise by syringe with rapid magnetic
stirring. The clear solution rapidly increased in viscosity
stopping the stirrer in about five minutes. After standing at room
temperature for three days, 75 mls. of methylene dichloride were
added with stirring to provide a viscous solution. The polymer was
precipitated in 800 mls. of methanol, filtered, washed with
methanol and dried to yield 987 mgs. of white crumb-like
product.
Elemental analysis for C.sub.22 H.sub.9 ClF.sub.6 O.sub.4 provided
the following:
______________________________________ % C % H % Cl % F
______________________________________ Calculated 54.29 1.86 7.28
23.42 Found 53.97 1.89 7.00 23.02
______________________________________
The polymeric product, obtained in 94% yield, contained the
following recurring structural units: ##STR30##
The polymer structure was confirmed by IR spectrophotometric
analysis.
Upon heating of the polymer to 350.degree. C. on a Fisher-Johns
melting point apparatus, the polymer softened slightly but did not
discolor. Thermogravimetric analysis showed that the onset of
decomposition in nitrogen occurred at 500.degree. C. Differential
scanning calorimetry failed to detect any transitions up to
325.degree. C. The polymer was soluble in methylene dichloride,
chloroform, TCE, tetrahydrofuran, dioxane, dimethylacetamide and
pyridine. The polymer was swollen by 1,2-dichloroethane, acetone,
benzene, chlorobenzene and ethyl acetate and was insoluble in
water, methanol and hexane.
The inherent viscosity (0.5 g./dl.) of the polymer in methylene
dichloride and in tetrahydrofuran was in each case 4.8 dl./gram.
The inherent viscosity of a solution of the polymer in lithium
chloride and dimethylacetamide (0.5 gram of the polymer of this
Example per 100 mls. of a solution of five grams LiCl per 100 mls.
of DMAC) was 0.95 dl./gram. Films that were cast from TCE onto
glass slides, allowed to dry at room temperature, soaked in
methanol to free the film from the glass and then dried were
relatively clear and exhibited a refractive index of 1.73. A
stretched film exhibited parallel and perpendicular refractive
indices, respectively, of 1.78 and 1.48.
EXAMPLE 6
This Example illustrates the polycondensation of
2,2'-bis(trifluoromethyl)biphenyl dicarbonyl chloride and
2,2'-bis(trifluoromethyl)-4,4'-dihydroxy biphenyl to provide
poly(2"2"'-bis(trifluoromethyl)-4",4"'-biphenylene
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate).
2,2'-bis(trifluoromethyl)-4,4'-dihydroxybiphenyl (388 mgs.) was
dissolved in two mls. of TCE and 0.5 ml. of pyridine under an argon
atmosphere. A solution of 500 mgs. of
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarbonyl chloride in two
mls. of TCE was added dropwise with stirring resulting in the
formation of a white emulsion. Tetrahydrofuran (35 mls.) was slowly
added to provide an almost-clear solution. Polymeric product was
precipitated in methanol, filtered, washed with methanol and dried
to yield 755 mgs. (94%) of a white polymeric material containing
recurring units of the formula ##STR31##
Elemental analysis for C.sub.30 H.sub.12 F.sub.12 O.sub.4 provided
the following:
______________________________________ % C % H % F
______________________________________ Calculated 54.23 1.82 34.31
Found 53.85 2.07 32.81 ______________________________________
The polymer exhibited solubility in tetrahydrofuran and in
dimethylacetamide. The polymer was not soluble in dichloromethane,
acetone, methanol, hexane or water. When heated to 350.degree. C.
on a Fisher-Johns melting point apparatus, the polymer did not
melt, flow or discolor. Inherent viscosity (0.5 g./dl.) in
tetrahydrofuran was 1.2 dl./gram.
EXAMPLE 7
This example illustrates the preparation of poly(ethylene
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate) by the
high-temperature melt polycondensation of ethylene glycol and
dimethyl 2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate.
In a ten-ml. two-necked pear-shaped flask (equipped with a drawn
glass capillary tube leading through the smaller neck to the bottom
of the flask and a column connected to a bubbler on the larger
neck), was added one gram of dimethyl
2,2'-bis(trifluoromethyl)-4,4'-biphenyl dicarboxylate; one ml. of
ethylene glycol; one mg. of calcium acetate monohydrate; and one
mg. of antimony trioxide. The flask was heated in a 150.degree. C.
oil bath while argon was slowly bubbled through the capillary tube
into the two-phase melt. After one hour, the mixture became a clear
single phase. The temperature was slowly raised to 180.degree. C.
while bubbling was continued for 16 hours. The column was then
replaced with a slow nitrogen sweep at the mouth of the larger neck
as the temperature was slowly raised to 210.degree. C. When most of
the excess ethylene glycol had distilled out, the larger neck was
connected to a vacuum pump through a needle valve and vacuum was
slowly applied as the temperature was raised to 230.degree. C.
Argon flow through the capillary was restricted by a pinch clamp on
the rubber supply tube, and after an additional one hour, full pump
vacuum was applied to the flask. The temperature was then slowly
raised to 260.degree. C. and the pinch clamp was gradually opened
as the polymeric reaction mass thickened. After an additional two
hours at 260.degree. C., the clamp was closed and the polymer was
held at 200.degree. C. under full pump vacuum for an additional 18
hours. The entire procedure required about 42 hours. Upon cooling,
a pale yellow, tough, bubbly polymer resulted. The polymer was
dissolved in acetone, precipitated in hexane to provide a
chunk-like material, redissolved in acetone, precipitated in water
to provide a fine powder and was redissolved in and freeze-dried
from benzene. After drying overnight under vacuum, the resulting
white foamed polymer weighed 946 mgs. (95% yield).
Elemental analysis for C.sub.18 H.sub.10 F.sub.6 O.sub.4 provided
the following:
______________________________________ % C % H % F
______________________________________ Calculated 53.48 2.49 28.20
Found 53.40 2.56 28.31 ______________________________________
The polymer contained recurring units of the formula ##STR32##
The polymer softened at 130.degree. C. on a Fisher-Johns melting
point apparatus. Polymer flow improved upon application of pressure
by hand at a temperature of 200.degree. C. Thermogravimetric
analysis showed that the onset of decomposition in nitrogen
occurred at 380.degree. C. Differential scanning calorimetry
detected a reproducible transition at about 120.degree. C.
Thermomechanical analysis also showed a softening temperature at
about 115.degree. C.
Inherent viscosity (0.5 dl./g.) in acetone was 0.20 dl./gram; in a
3/2 phenol/TCE solvent mixture, it was 0.28 dl./gram.
The refractive index and Abbe number for an isotropic film cast
from acetone and measured on an Abbe refractometer were,
respectively, n=1.5218 and .nu.=29. The parallel and perpendicular
refractive indices of a fiber pulled from a polymer melt were
respectively 1.546 and 1.507.
* * * * *